DE2352876A1 - PROCEDURE FOR WATER PURIFICATION AND WATER PURIFICATION SYSTEM FOR CARRYING OUT THE PROCEDURE - Google Patents

Description

1A-548 ■

PAYEL POLASEK, Johannesburg,

Transvaal Province, Republic of South Africa

Process for clarifying water and water treatment plant for
Implementation of the procedure

The invention relates to a method for clarifying water in a sludge bed sewage treatment plant and a water treatment plant for carrying out the method with at least one venting zone and; with at least one sludge bed zone downstream of the ploculation;

i zone. - ι

Sewage treatment plants of this type with one or more sludge beds I

zones are known. Some of these sewage treatment plants have separate ones!

Plocculation zones in which pre-flocculation takes place; whereupon the plogging continued in the mud bed zones

will. In other known sewage treatment plants, none are separated |

th ploculation zones provided. That with coagulant, j

offset water enters directly into sludge bed zones where the {

entire allocation process takes place. j

None of the known sewage treatment plants works under optimal conditions

conditions for complete allocation, so that the allocation

tion often still takes place in the filters or in the downstream j

water reservoirs from the sewage treatment plants; is set. , '

; The porting of the population downstream z. B. in the sludge bed zones is a significant disadvantage which one
ί Use of 'organic populating aids (OPA) (polyelectrolysis) is not permitted in the sewage treatment plants', The organic

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Flocculating aids are always short of the water to be treated .after. Addition of the coagulant added. One reason for this addition of the organic flocculation aids is a requirement that they be uniform in the treated water Achieve distribution. However, this largely depends on the construction of the flocculation zone and τοη the mixing speed during flocculation. Hence it is with sewage treatment plants Without a flocculation zone, the organic ones are not possible Add flocculation aids under optimal conditions,

d. H. Addition and homogenization in the water when the flocculation has reached the optimum. When adding the organic Flocculation aids become large and solid aggregates formed, which arise only under the above optimal conditions.

The well-known sewage treatment plants with more than one sludge bed zone additionally have other disadvantages which reduce their broad applicability in practice. With these plants a separate population zone upstream of the sludge bed zones provided in which the flocculation by purely hydraulic energy distribution due to the inflowing Water takes place. The water entering the mud bed zone of reached the flocculation zone, is pre-flocculated differently, due to different dimensions of the flocculation zones (i.e. different specific volumes) and therefore the amount of energy distributed is different. The flow distribution of the flow in the Elokkula- tion zone and the flow into the sludge bed zones (if they caused only by distribution pipes connected to the raw water inlet) is very non-uniform and does not ensure the same specific flow through the mud bed zones (i.e. the same upward flow velocity) the sludge bed levels). Such a one Distribution changes with differences in the amount of water, which flows up (changing pressure losses in the pipes or the like). The operation of such a sewage treatment plant is unstable and the setting of the respective flow through the

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individual sludge bed zones relative to the change in the flow rate is complicated and tedious.

So far, the dissolution or distribution of the organic i Flocculating aids of various kinds caused by] it dissolves in distilled water or in drinking water (if necessary with the addition of alcohol), which j lyte form for the organic elimination aids. The solubility of the polyelectrolytes, which are in powder form or in gelatin form present is very low in these electrolytes | (the process of dissolution takes a few hours) and furthermore requires the application of the solutions prepared in this way requires a high dose of organic elimination aids, depending on the type of the polyelectrolyte used.

It is therefore the object of the present invention to provide a method for water clarification, which the use of organic flocculation aids allowed under optimal conditions and leads to a quick and highly effective clarification of the water, as well as a water purification plant to carry out .. this procedure.

This object is achieved in that the essentially completely flocculated water with a organic elimination aid added to support the agglomeration process and fed to the sludge bed zone in which the suspension is separated.

The sewage treatment plant comprises one or more separate sludge. bed zones. The flocculation zone is designed in such a way that that organic elimination aids can be used under optimal conditions. The water flow becomes proportional distributed over all sludge bed zones. In the mud bed zone there is essentially no eloculation by the primary coagulants. The sludge bed zone is only used the agglomeration of the flakes already formed. The flakes have been formed by flocculation or precipitation.

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The organic flocculating aid forms polymer bridges between the individual flakes. The term "primary coagulant" means coagulant which destabilizes of the particles in the source water. The water entering the respective sludge bed zone is either flocculated (if no organic flocculating aids are used) or with the addition of organic flocculating aids flocculated or homogenized. The water leaving the flocculation zone is distributed to the individual sludge bed zones, exactly proportional to the surface areas the liquid level in the sludge bed zones. The water thus distributed either flows through zones for uniformization the flow upstream of the sludge bed zones or directly to the inlet at the bottom of the sludge bed zone (in the case of a single sludge bed zone).

The flocculation in the flocculation zone is supported by the rotation of a stirrer. The flocculations will either at a uniform value of the velocity gradient (more than 100 see "if organic flocculating aids are used) or at different values of the velocity gradient. In the latter case, can the speed gradient above or below 100 see " lie. Furthermore, according to the invention, the polyelectrolytes are activated by preparing their solution with soft water, which is either very weakly acidic or very weakly alkaline.

In the following the invention is explained in more detail with reference to drawings.

Show it:

Fig. 1a is a schematic cross section through a first embodiment of the water treatment plant according to the invention j

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Pig. "1" b is a partial plan view of the invention Sewage treatment plant according to Figure 1a in section along the line b-b;

Pig. 2a shows a schematic side view of a second embodiment the water treatment plant according to the invention in section;

2b shows a partially schematic representation of the embodiment 2a in section along the line b-b;

3a shows a schematic side view of a third embodiment the water treatment plant according to the invention] in section;

3b shows a schematic partial view of the embodiment according to FIG. 3a in section along the line b-b; and

4 shows a schematic cross section of a further embodiment the water treatment plant according to the invention.

A device for clarifying waste water by chemical treatment is shown in Figures 1a and 1b. This device comprises seven different zones, namely a flocculating zone 1, which one after the other in the circumferential direction from a flow unification zone 2, a sludge layer zone 3, a sludge thickening zone 4, one Sludge layer zone 5 and a flow unification zone 6 is surrounded. above zones 3, 4 and 5 is found a protection zone of clear water 7. At the bottom of the flocculation zone 1 an inlet pipe 8 is provided for the inlet of the water to be treated. In flocculation zone 1 there is a stirrer 9. In the upper area of the flocculation zone 1 above the stirrer 9 there is a partition 10 (or a guide element) which forms a neck part / of the vessel

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det. A metering device 12 for adding organic flocculating aids (Oi ¹ A) is provided between the stirrer 9 and the partition wall 10. This device 12 is connected to a pipeline 13 which leads to metering devices.

A distribution trough 14 is located above the partition wall 10 in the water level of the flocculating zone 1. This trough 14 is divided by inserted partition walls 15 into an equal number of separate chambers 16 and 17 of different sizes, which alternate with one another. The chamber 16 has an overflow edge 18 and the chamber 17 has an overflow edge 19. Both edges 18 and 19 are located radially inward of the flocculating zone 1 and both are flat. The ratio of the lengths of the overflow edges 18 and 19 or the sums ( Σ ^ 18 and 2LJ 9) of the lengths is determined according to the direct ratio of the surfaces of the functionally assigned sludge bed levels 30 and 31, ie 18:19 or rather Σ. 18 ι Σ 19 = 30: 31 or 18, Σ 18: 30 = 19, ^ 19: 31.

The chambers 16 and 17 are connected via pipes 22 and 23, respectively connected to the troughs 20 and 21 to standardize the flow. The overflow edges of the troughs 20 and 21 are on the height of the water level of the protection zone 7 of clarified water, whereby the trough is either inside or also located outside this zone. The flow unification troughs 20 and 21 are overflow edges 24 and 25 (which extend in the circumferential direction around the entire respective trough) connected to connecting channels 26 and 27. The channels 26 and 27 are arranged in the circumferential direction around the axis of the forming zone 1. One wall of the connection channels 26 and 27 thus forms the overflow edge 24 "and 25, respectively, and in this way the upper zone of the tank is made from the troughs 20 and 21 with the flow unification zones 2 or 6 connected.

The flow unification zones 2 and 6 are at the bottom

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in connection with the sludge bed zones 3 and 5 and their upper conical extensions. This connection is through narrow slots 28 and 29 made. The sludge thickening zone 4, which is assigned to both sludge bed zones, is located between the two mud bed zones. Levels 30 and 31 of sludge bed zones 3 and 5 are through overflows' 32 and 33, through which the sludge bed zones are connected to the sludge thickening zone 4.

Below overflows 32 and 33 "and within the sludge thickening zone 4 guide elements 34 and 35 are provided. Between the guide elements 34 and 35 in the upper region of the Sludge thickening zone 4 is a perforated manifold 36 intended.

The zone 7 with clarified water is located above the sludge bed zones 3, 5. A system of collecting channels 37 are provided at the level of zone 7 with clarified water. Perforated drainage pipes 38, 39 and 40 are located on the floor the sludge thickening zone 4 or the flow uniting zones 2 and 6.. ·

Wastewater is treated in the following manner with the apparatus described.

Raw water to which coagulants have been added enters the flocculation zone through the inlet pipe 8. By . the movement of the stirrer 9 causes a sufficient energy distribution in the water, so that the flocculation process is completed and in the flocculation zone 1 reached an optimum. The flocculation optimum can, for. B. are expressed by the optimal value of the Peld number for a given amount of water and a given amount of coagulation! ttel. The organic flocculating aid becomes the flocculated Water supplied from a dosing tip 12. The rotation of the Water mass due to the rotation of the stirrer 9 and also the flow of water through the narrowed opening 11

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causes a great deal of turbulence, which results in the mixing and uniform distribution (homogenization) of the feed Flocculating aid is used in the flocculated water. The agglomeration process. the flocculated particles, due to Polymer chain bridging, "starts immediately after addition and homogenizing the organic flocculating aid in the flocculated water. Above the partition wall 10, the Water proportionally overflows onto the surfaces of the liquid levels 30 and 31 'of the sludge bed container the overflow edges 18 and 19 distributed in the compartments 16 and 17. The water then flows from compartments 16 and 17 into the corresponding flow unification troughs 20 and 21 via pipes 22 and 23, respectively. From these troughs 20 and 21, the water is distributed uniformly over the edges 24 and 25 and enters flow unification zones 2 and 6 via channels 26 and 27, respectively. Here is an agglomeration instead and the flow velocity is further unified.

The water from zones 2 and 6 enters the bottom of the sludge bed zones 3 and 5 through narrow slots 28 and 29. Agglomeration continues in the sludge bed. Due to the high speed and great turbulence at the inlets 28 and 29 to the sludge bed zones 3 and 5, the sludge bed is kept completely in the poured state or fluidized bed state. Submerged overflow edges 32 and 33 determine the level of the sludge bed. The excess flocculation suspension of the sludge bed flows into the sludge thickening zone 4 when levels 30 and 31 are exceeded. This flow makes up about 10-10 to 50 $ of the total flow through the apparatus. The excess amounts of flocculated suspension of the sludge bed are continuously carried along by the water flowing into the sludge thickening zone. By means of guide elements 34 and 35, the incoming flow is guided downwards into the sludge thickening zone 4, where the flakes and the clarified water are separated off.

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The pipe 36 serves as a collecting pipe for the clarified water, which is fed to the filters together with the main amount of outflowing water. That is in the sludge thickening zone 4 settling sludge concentrate is periodically replaced by a Pipeline 38 withdrawn. The main amount of clarified water in the upper zone 7 is discharged through the collecting lines 37. The pipes 38, 39 »40 and 8 can be used for this each of the zones 1 to 7 or the entire sewage treatment plant to drain.

FIGS. 2a and 2b show devices which are similar to those according to FIGS. 1a and 1b. With this alternative Embodiment of the invention is the main difference to the above-described embodiment in the formation of the partition wall 10, which has an outlet channel 41 between the flocculation zone 1 and the neck area 11 together with a further additional partition 42 forms. The partition 42 can be attached to the agitator shaft 9 so that an interface of the connection channel 41 rotates. Alternatively can the partition wall 42 can also be attached to the partition wall 10 by transverse ribs, thereby forming a stable channel area will. Further, the distribution trough 14 is from the flow unification trough 20 separated only by a partition 44. Each area 16 on the side of the wall 44 is either with an overflow edge 45 or provided with holes in the wall 44. The chambers 16 are directly with. the flow unification trough 20 connected, while the chambers 17 via tubes 23 with are connected to the trough 21, as already described with reference to FIGS. 1a and 1b.

The mode of operation of the embodiment according to FIGS. 2a and 2b is basically the same as the mode of operation of the embodiment according to Figures 1a and 1b.

Figures 3a and 3b show a further embodiment similar to those according to FIGS. 1a and 1b or 2a and 2b. In this alternative embodiment of the invention lies

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the essential difference to the previously "described embodiments in the formation of the locking zone 1, in which the water flows downwards. In the flocculating zone 1 a vessel 46 is provided, whereby a space 47 between two vessels. In the space 47 is the outlet 41 between inserted ribs which form the partition 10 hold, provided. In this alternative embodiment, the bottom of the vessel 46 is supported by the partition 10 the neck region 11 is formed. Another partition wall 49, which is larger than the neck area 11, lies above the neck area 11. The partition wall 49 is held by ribs 48 which extend over the neck area 11 to the partition wall 49. The dosing tip 12 is located above the dividing wall 10. The space 47 is with the water level of the | Flocculating zone 1 connected and the vertical wall of the vessel 46 has overflow edges 18 and 19 of the areas 16 and Another difference is the direct connection of chambers 16 and 17 with the upper areas of the flow- Standardization zones 2 and 6 by pipelines 22 and 23, respectively.

The mode of operation of this embodiment according to FIGS. 3a and 3b is basically the same as the mode of operation of FIG Embodiment according to Figures 1a and 1b.

4 shows a further embodiment of the invention. In this embodiment, only four separate functional zones are provided, namely a flocculating zone 1, surrounded by a sludge bed zone 3 and a sludge thickening zone 4 and above a clear water zone 7. The inlet pipe 8 is located in the upper area of the flocculating zone 1. The flocculating zone 1 is through Partition walls 50 divided into several compartments 51. Each of the partition walls 50 has an opening 52 at least in the middle, via which adjacent compartments 41 are connected to one another. The shaft of the stirrer 9 extends through these openings 52. In each compartment 51 there is a stirrer 9 _f, however

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of different sizes or of different training. Entertains) of the stirrer 9 is the partition 10 with the neck area 11 provided. Through the partition 10 and the floor of the flocculating zone 1 a space 47 is defined. The bottom area of the flocculating zone 1 is through the neck area 11, the Intermediate space 47 and furthermore connected to the bottom area of the sludge bed zone 3 by narrow gaps 48. The gap 47 is supported by ribs 48, which also form the partition wall 10 wear, divided into outlet channels 41 which extend to the narrow slot 48. Above the neck area 11 there is another partition wall 49, which extends over the neck region 11 extends out and which also supported by the ribs 48. At least one metering device 12 for adding organic flocculating aid is located in the bottom area of flocculating zone 1 above the partition 10. The further development of this embodiment is similar to that according to FIGS. 1a and 1b.

The mode of operation of this embodiment according to FIG. 4 is basically the same as that according to FIGS. 1a and 1b. In this alternative embodiment of the invention the main difference in the way of working in relation to the previous execution forms in the process of the flocculation process and in the direct entry of the flocculated and / or flocculated water into the sludge bed. The water flows one after the other through the compartments 41 of the flocculating zone 1, where it is set in strong motion by the stirrer 9 is moved. Due to the different size or type of Ruhr era 9 (the rotation is through a common Wave conveyed) the flocculating water in each compartment 51 is stirred with different energies. Thus finds flocculation takes place under different conditions in each compartment.

This design of the Plokkulierzone one makes a simple change of Flokkulierbedingungen from the standpoint of energy ^N distribution possible. This is important for an eventual

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Clarification without the addition of organic flocculating aid. In the event of clarification without the use of organic flocculants For help, it may be unnecessary to provide the partition wall 10 and water (possibly with a slight twisting movement) enters directly through the narrow slots 28 in the bottom area of the mud bed zone. Compartment for the addition of organic flocculating aid the flocculated water enters the sludge bed zone 3 with a homogeneously distributed organic flocculating aid. water flows through the neck region 11, the space 47 and the outlet channels 41 directly through the narrow slots 48 into the Bottom area of the sludge bed zone 3. The movement of water caused by the stirrer 9 and the abrupt change in the The direction of flow due to the partition 49 and the bottom of the flocculating zone 1 ″ causes a great deal of turbulence, which the mixing and homogenization of the organic flocculating aid is beneficial in flocculated water. In the outlet ducts 41 (below the narrow slot 48) the rotational energy of the water is distributed and the flow becomes calm. The agglomeration process takes place in the sludge bed zone 3.

The invention has been described above on the basis of a device with a circular cross-section. However, it is It will be readily apparent that other devices with other cross-sectional shapes (e.g. rectangular cross-section) will do the same can be used well.

The present invention offers significant advantages over conventional methods and devices; Some of these The advantages are explained below:

In the separate flocculation zone, the favorable Maintain the most favorable conditions for clotting in the water. In the case of a device with more than one sludge bed zone, the flocculation zone is common for all sludge - bed zones are provided and the flocculated water is proportional distributed over the mud bed zones so that in each

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Lamb bed zone flows the same specific outlet volume, what is required from the standpoint of maximum output.

Agitation in the flocculation zone distributes enough energy to bring about the completion of the flocculation in this zone. All the different embodiments of the flocculation zone allow optimal use of the organic flocculation aid in the clarification process. The creation of optimal conditions for the use of the organic flocculation aid allows the use of a high uniform velocity gradient (greater than 100 seconds) "in performing the entire flocculation process. This leads to a substantial acceleration of the clarification process, ie to an increase in the output water quantity of the device (by more than 100%) and at the same time a reduction in the overall dimensions of the apparatus (by more than 50% ) . The formation of the flocculation zone , so that the flocculation process takes place one after the other at different values of velocity gradients, is important for a clarification treatment without the use of organic flocculation aid. This leads to a considerable improvement in the flocculation conditions, to a reduction in the dimensions of the flocculation zone. which normally serves to distribute the coagulant in the treated water.

That from a common flocculation zone into the mud beds Incoming water is flocculated or pre-flocculated in the same way. At the point of supplying the organic Flocculating aid, the total amount of water is homogenized with the organic flocculating aid in the same way. In each of the sludge beds, clarified water of the same quality is formed and thus the facility works under

the optimal conditions.

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The advantages of the "distribution trough are its simplicity, the easy controllability, the avoidance of major disturbances and the great accuracy of the water distribution, regardless of the current. The accurate power distribution in each of the mud beds proportional to the liquid levels therein ensures the same specific output power of all sludge beds and thus a maximum output power of the overall apparatus in the case of stable operation.

A major improvement in the manufacturing process of the polyelectrolyte solutions consists in the activation of the polymer chains, which leads to an improvement in the solubility leads, d. H. a shorter dissolution time and sometimes the viscosity of the solution is also affected. the The performance of the polyelectrolyte is significantly improved, that is, lower dosages are required to achieve the desired effect.

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Claims (10)

PATESTIC PROVISIONS 1 / method for clarifying water in a sludge bed sewage treatment plant, characterized in that the essentially completely flocculated water with an organic Flocculating aid to support the agglomeration process added and fed to the sludge bed zone, in which the suspension is separated. 2. The method according to claim 1, characterized in that the flocculated water is proportional to several sludge bed zones to the respective liquid surface in the sludge bed zone is distributed. 3. The method according to any one of claims 1 or 2, characterized characterized in that the flow of flocculated water is kept uniform. 4. The method according to any one of claims 1 Ms 3, characterized characterized in that a solution of the flocculating aid in soft water with a non-neutral pH value is used. 5. Water treatment plant with at least one plowing zone and at least one sludge bed zone downstream of the flocculating zone, characterized by an inlet (12,13) for an organic flocculating aid in front of the sebum bed zone (3.5), through one flow zone (2.6) each for making it smooth the flow between the occlusion zone (1) and the sludge beds (3,5) and through a sludge thickening zone (4) downstream of the sludge bed zone (3,5). 6. Water treatment plant according to claim 5, characterized in that a JPlokkulierzone (Ϊ) at least two sludge bed zones (3,5) are connected downstream, with the water of the flocculation zone (1) the individual sludge bed zones (3,5) depending on the size of the liquid level in the individual Sludge bed zones (3.5) is supplied. 409822/0719 7. Water treatment plant according to claim 6, characterized in that the sludge bed zones (3.5) at a radial distance each other surround the flocculating zone (1) and that between the sludge bed zones (3, 5) a common sludge thickening zone (4) is provided. 8. Water treatment plant according to one of claims 5 to 7, characterized by guide elements (10, 42) at the outlet of the flocculation zone (1) for the even distribution of the flocculation aid. 9. Water treatment plant according to one of claims 5 to 8, characterized by a distribution trough (20,21) between the outlet of the flocculating zone (1) and the inlet of the flow zone (2,6). 10. Water treatment plant according to claim 9, characterized by overflow edges (18, 19) at the inlet of the distribution trough (20, 21) and by partition walls (15) which subdivide the distribution trough (20, 21) into several compartments (16, 17). and divide the overflow edges (18, 19) into several sections, the respective lengths of which are directly proportional to the sizes of the liquid levels of the associated mud bed zones (3,5). 409822/0719 Blank page